Compact image forming apparatus with simplified cover

ABSTRACT

An image forming apparatus includes a structure having an image formation device to form an image, a cover pivotally attached to the structure around a rotary shaft, and an opening angle restricting device to restrict an opening angle of the cover regarding the structure. The opening angle restricting device includes a pivotable cover rotation restriction member coaxially arranged with the rotary shaft to contact a downstream side of the pivotable cover in a cover opening direction at its first end to restrict the rotation of the pivotable cover in the opening direction.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35U.S.C. §119 to Japanese Patent Application No. 2012-064802, filed onMar. 22, 2012 in the Japan Patent Office, the entire disclosure of whichis hereby incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to an image forming apparatus, such as acopier, a printer, a facsimile machine, etc.

2. Related Art

In a conventional image forming apparatus, an image forming unit, suchas a photoconductor unit, an intermediate transfer unit, etc., isincluded in a structure of an apparatus main body and is attached anddetached to and from the structure by opening a pivotable cover toexecute maintenance and replacement of the image forming unit or thelike.

According to an image forming apparatus described in Japanese PatentApplication Publication No. 2010-14813 (JP-2010-14813-A), by opening apivotable cover openably attached to a structure of an apparatus mainbody around a rotary shaft, a photoconductor unit is detached from thestructure.

JP-2010-14813-A also describes an opening angle rotation restrictingdevice for restricting an opening angle of the pivotable cover to aprescribed angle. Specifically, a damper is provided to limit swingingof the pivotable cover in an opening direction. One end of the damper issupported by a widthwise end of the structure around a shaft, while theother end thereof is supported by a widthwise end of the pivotable coveraround another shaft. Thus, when the pivotable cover is opened and thedamper is suspended between the structure and the pivotable cover, thepivotable cover does not open restricting the opening angle of thepivotable cover regarding the structure.

However, when the pivotable cover is opened regarding the structure, thedamper occupies a space at the widthwise end of the structure betweenthe pivotable cover and the structure by an amount equal to a width ofthe damper. Therefore, to attach and detach the photoconductor unit toand from the structure while preventing the photoconductor unit frominterfering with the damper, the sum of a width of the photoconductorunit and the width of the damper is required as a width of thestructure, thereby enlarging the image forming apparatus as a problem.

SUMMARY

Accordingly, the present invention provides a novel image formingapparatus that comprises a structure having an image formation device toform an image, a cover pivotally attached to the structure around arotary shaft, and an opening angle restricting device to restrict anopening angle of the cover regarding the structure. The opening anglerestricting device includes a pivotable cover rotation restrictionmember coaxially provided with the rotary shaft to contact a downstreamside of the pivotable cover in a cover opening direction at its firstend to restrict the rotation of the pivotable cover in the openingdirection.

In another aspect of the present invention, the pivotable cover rotationrestriction member further includes a second end contacting a contactsurface provided in the structure, the second end being arranged on anopposite side of the rotary shaft to the first end. When the pivotablecover is opened and the first end of the pivotable cover rotationrestriction member contacts the downstream side of the pivotable coverin the cover opening direction, the pivotable cover rotation restrictionmember is pressed and rotated by the pivotable cover around the rotaryshaft, while the second end of the pivotable cover rotation restrictionmember contacts the contact surface of the structure and stops rotatingand supports the pivotable cover by restricting rotation and an openingangle of the pivotable cover in the opening direction regarding thestructure.

In yet another aspect of the present invention, the pivotable coverrotation restriction member has a prescribed shape determining arelation that a portion of the first end is heavier than a portion ofthe second end across the rotary shaft.

In yet another aspect of the present invention, the pivotable coverrotation restriction member has a prescribed shape determining arelation that a portion of the first end is lighter than a portion ofthe second end. The structure includes a protrusion section is providedto contact and restrict rotation of the pivotable cover rotationrestriction member when the pivotable cover is closed.

In yet another aspect of the present invention, a spring is provided toconnect the pivotable cover rotation restriction member with thepivotable cover to cause an angular moment on the one side of thepivotable cover rotation restriction member around the rotary shaft. Thepivotable cover rotation restriction member is shaped so that a portionof the first end is lighter than a portion of the second end across therotary shaft.

In yet another aspect of the present invention, an elastic member isdisposed at at least one of a first contact point on the downstream sideof the pivotable cover in its opening direction contacted by thepivotable cover rotation restriction member, and a second contact pointon the contact surface of the structure contacted by the pivotable coverrotation restriction member.

In yet another aspect of the present invention, the pivotable coverrotation restriction member includes a plate spring contacting thedownstream side of the pivotable cover in its opening direction when thepivotable cover is opened.

In yet another aspect of the present invention, multiple holes areformed in the pivotable cover, the structure, and the pivotable coverrotation restriction member, respectively, to collectively acceptinsertion of the rotary shaft when assembled. A holder section isdisposed in the pivotable cover to hold the pivotable cover rotationrestriction member to align the respective holes of the pivotable cover,the structure, and the pivotable cover rotation restriction member onthe same linear line, substantially.

In yet another aspect of the present invention, an opening angleadjusting device is provided to adjust the opening angle of thepivotable cover regarding the structure restricted by the opening anglerotation restricting device.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of theattendant advantages thereof will be more readily obtained assubstantially the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 is an enlarged view illustrating a rotation restriction memberand its vicinity when a front cover is opened;

FIG. 2 is a schematic diagram illustrating a printer according to oneembodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a configuration of theprinter with the front cover opened;

FIG. 4 is a schematic perspective view illustrating an image formingapparatus when the front cover thereof is opened;

FIG. 5A is a side view illustrating the rotation restriction member andits vicinity when the front cover is opened;

FIG. 5B is a side view illustrating the rotation restriction member andits vicinity when the front cover is closed;

FIG. 6A illustrates an aspect in which a replacement unit is located ona structure side when the front cover is opened;

FIG. 6B illustrates an aspect in which the replacement unit is partiallymoved toward the front cover side from the structure side when the frontcover is opened;

FIG. 7 is a side view illustrating the rotation restriction memberaccording to one embodiment of the present invention;

FIG. 8A is a diagram illustrating an aspect when the front cover isopened;

FIG. 8B is a diagram illustrating an aspect when the front cover isclosing;

FIG. 8C is a diagram illustrating an aspect when the front cover hasbeen closed;

FIG. 9A is a diagram illustrating an aspect when the front cover isopened;

FIG. 9B is a diagram illustrating an aspect when the front cover isclosing;

FIG. 9C is a diagram illustrating an aspect when the front cover hasbeen closed;

FIG. 10 is an enlarged view illustrating the rotation restriction memberand its vicinity when an elastic member is attached to a contact surfacebetween the structure and the front cover to reduce an impact;

FIG. 11A is a diagram illustrating an aspect when the front cover isopening;

FIG. 11B is a diagram illustrating an aspect when the front cover hasbeen opened;

FIG. 12A is an enlarged perspective view illustrating the rotationrestriction member and its vicinity when the front cover is opened;

FIG. 12B is an enlarged perspective view illustrating the front cover;

FIG. 13 illustrates an aspect when the rotation restriction member isheld by a restriction member holding section included in the frontcover;

FIG. 14A is an enlarged view illustrating the rotation restrictionmember and its vicinity when a front cover angle adjustment screw isattached to a front cover frame section and the front cover is opened;and

FIG. 14B is a diagram illustrating an aspect when an opening angle issmaller than that in a state of FIG. 14A.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views thereofand in particular to FIG. 2, a schematic configuration of a printer 100as an image forming apparatus according to one embodiment of the presentinvention is described. The printer 100 of this embodiment is a colorprinter of a tandem type with an image forming unit 60 located at acenter of an apparatus main body 50 and a sheet feeding unit 20 locatedbelow the image forming unit 60 to feed a sheet to form an image thereonby the image formation unit 60.

In the image formation unit 60, multiple drum-shaped photoreceptors 3Y,3M, 3C, and 3Bk are provided as image carriers. Each of thephotoreceptors 3Y, 3M, 3C, and 3Bk forms a toner image having adifferent color. In an illustrated example, yellow, cyan, magenta, andblack toner images are formed in respective surfaces of thephotoreceptors 3Y, 3C, 3M, and 3Bk. Each of the photoreceptors 3Y, 3M,3C, and 3Bk is placed parallel to each other at a prescribed interval.An intermediate transfer belt 64 is located being opposed to lowersections of these photoconductors 3Y, 3M, 3C, and 3Bk as an intermediatetransfer member. Here, as the intermediate transfer member, a drum typecan be used. However, as illustrated in the drawing, an endless beltwound around multiple support rollers 65 and 66 is typically driven in adirection as shown by arrow in the drawing.

On the peripheries of the respective photoreceptors 3Y, 3Y, 3C, 3M, and3Bk, there are provided charging devices 7Y, 7M, 7C, and 7Bk each forapplying a charging process to the surface of each of the photoreceptors3Y, 3Y, 3C, 3M, and 3Bk. An exposure unit 8 is provided to expose thephotosensitive surfaces with laser light based on image information.Also provided on the peripheries are developing devices 9Y, 9M, 9C, and9Bk for developing latent images formed on the surfaces of thephotoconductors 3Y, 3C, 3M, and 3Bk after the exposure of the exposureunit 8 with toner included in developer to visualize the latent imagesinto toner image, multiple primary transfer rollers 10Y, 10 M, 10C, and10Bk respectively facing the photoconductors 3Y, 3M 3C, and 3Bk via theintermediate transfer belt 64, and cleaning devices 11Y, 11M, 11C, and11Bk for removing residual toner remaining on the surfaces of thephotoconductors 3Y, 3C, 3M, and 3Bk after respective transfer processesexecuted onto the intermediate transfer belt 64.

When image formation starts in the printer 100, the photoreceptors 3Y,3M, 3C, and 3Bk are driven and rotated clockwise in the drawing. At thismoment, the surfaces of the respective photoreceptors 3Y, 3M, 3C, 3BKare charged by the charging devices 7Y, 7M, 7C, and 7Bk each to have aprescribed polarity. Subsequently, laser light is emitted from theexposure device 8 to the charged surface based on image information, sothat a latent image is formed on each of the photoconductors 3Y, 3M, 3C,and 3Bk. Further, the latent images formed on the surfaces of thephotoconductors 3Y, 3C, 3M, and 3Bk are visualized by the developingdevices 9Y, 9M, 9C, and 9Bk as toner images. The toner images are thentransferred by the primary transfer rollers 10Y, 10M, 10C, and 10Bk, toeach of which a bias is applied from a power source, not shown, onto theintermediate transfer belt 64 from the photoconductors 3Y, 3M, 3C, and3Bk, respectively. Residual toner adhering to the surface of each of thephotoreceptors 3Y, 3M, 3C, and 3Bk after transferring of the toner imageis removed by each of cleaning devices 11Y, 11M, 11C, and 11Bk,respectively, and is collected in a waste toner tank 17 disposed belowthe intermediate transfer belt 64.

When a color image is formed, the above-described image formationprocess is executed in all of the photoreceptors 3Y, 3M, 3C, and 3Bk.Thus, yellow, cyan, magenta, and black toner images formed on therespective photoconductors 3Y, 3M, 3C, and 3Bk are transferred andsuperimposed in an order onto the intermediate transfer belt 64.Further, in the printer 100, a secondary transfer roller 12 is deployedfacing a support roller 66 across the intermediate transfer belt 64. Abias is applied from a power source, not shown, to the secondarytransfer roller 12.

On the other hand, in the sheet feeding unit 20 placed below the imageformation unit 60, there are provided a sheet feeding tray 21 to stacksheets S consisting of transfer sheets or plastic films and the like, afeeding roller 22 that launches a sheet S stacked on the sheet feedingtray 21, a Friction pad 23 as an isolation member to isolate double fedsheets, and a re-conveyance path 24 used when a double-sided image isformed. Furthermore, the isolated member can be a reverse rolleremploying a torque limiter system.

The sheet S fed from the sheet feeding unit 20 is further sent towardthe pair of registration rollers 13 and collides and stops being alignedthere. The pair of registration rollers 13 resumes rotation at aprescribed timing to cause a tip of the sheet S to synchronize with thecolor toner image formed on the intermediate transfer belt 64 in asecondary transfer station in which the secondary transfer roller 12 andthe intermediate transfer belt 64 contact each other, and feeds thesheet S toward the second transfer unit.

The sheet S with the toner image thus transferred in the secondarytransfer station is sent to the fixing device 14 having a fixing roller14 a, and the toner image is fixed onto the sheet S. The sheet S isexhausted thereafter onto a sheet loading section 16 provided on the topof the apparatus main body 50. Toner remaining and attaching to thesurface of the intermediate transfer belt 64 after the transferringprocess of the toner image is removed by the cleaning device 15 and iscollected in the waste toner tank 17.

In the printer 100 shown in FIG. 2, a right side thereof corresponds toa front side of the printer 100. A front frame of the apparatus mainbody 50, i.e., a front cover 30 as an pivotable member is capable ofpivotable movement around a fulcrum 31 between a closed position asshown in FIG. 2 and an open position as shown in FIG. 3. A unit mainlyconsisting of several parts is installed in the front cover 30. In thisembodiment, the unit is a conveyance unit 40 with the pair ofregistration rollers 13 that conveys sheets fed from the sheet feedingunit 20 toward the secondary transfer station. Further, the conveyanceunit 40 includes the pair of registration rollers 13, the secondarytransfer roller 12, one of guide plates of a re-conveyance path 24.

When maintaining the intermediate transfer belt 64 or detaching orattaching the waste toner tank 17 from or to the printer 100 organizedin this way, the front cover 30 is opened as shown in FIG. 3. Forexample, the intermediate transfer belt 64 is ejected by sliding anintermediate transfer unit including the intermediate transfer belt 64and the cleaning device 15 in a direction as shown by arrow A in thedrawing from the opening O.

FIG. 4 is a schematic perspective view illustrating the printer 100 whena front cover thereof is opened. The front cover 30 is swingably held bya structure 2 of the printer 100 around a fulcrum 31 thereof. The frontcover 30 is closed when the printer 100 is operating. When a replacementunit, such as a waste toner case, an intermediate transfer body, etc.,is replaced, the front cover 30 is opened as shown in FIG. 4.

A rotation restriction member 70 is swingably held around the fulcrum 31when the front cover 30 is opened to restrict an angle of the frontcover 30 as shown in FIG. 1.

Further, as shown in FIG. 5A, when the front cover 30 is released (i.e.,opened), the rotation restriction member 70 and a contact surface 2 b ofa structure front cover holding section 2 a contact each other, whilethe rotation restriction member 70 and a contact surface 30 b of thefront cover frame 30 a contact each other. Specifically, the rotationrestriction member 70 is configured to bear the weight of the frontcover 30. With this, an opening angle of the front cover 30 isrestricted.

On the other hand, when the front cover 30 is closed from an openingstate, the rotation restriction member 70 rotates around the fulcrum 31and assumes a posture as shown in FIG. 5B. Thus, even when the fulcrum31 is disposed close to an edge of the front cover 30 and the frontcover 30 is closed, the rotation restriction member 70 is not exposedfrom the front cover 30.

Further, as shown in FIG. 6A, the rotation restriction member 70 islocated below the contact surface 30 b of the front cover 30 when thefront cover is opened. With this, as shown in FIG. 6B, a space above thefulcrum 31 is widely used as a replacement area for the replacement unit5.

FIG. 7 is a side view of the rotation restriction member 70. When ashape of the rotation restriction member 70 determines that weight of afront cover side of the rotation restriction member 70 is heavier thanthat of a structure side thereof located across the fulcrum 31, anangular moment works on the rotation restriction member 70 clockwisearound the fulcrum 31 as shown in FIG. 7.

Now, an aspect when the front cover 30 is closed regarding the structure2 is described on condition that the shape of the rotation restrictionmember 70 determines that weight of the front cover side of the rotationrestriction member 70 is heavier than that of the structure side thereoflocated across the fulcrum 31.

When the front cover 30 becomes a closed state from the opening state,the rotation restriction member 70 and the contact surface 2 b keepcontact each other from the opening state until the front cover 30 andthe structure make a given angle therebetween. Then, the front cover 30swinging in a closing direction around the fulcrum 31 contacts therotation restriction member 70, and depresses the rotation restrictionmember 70. Thus, the rotation restriction member 70 starts rotationcounterclockwise as shown in FIG. 7 around the fulcrum 31. When thefront cover 30 is closed regarding the apparatus main body, the rotationrestriction member 70 keeps its own posture contacting the front cover30.

Thus, as shown in FIG. 5, an end of the rotation restriction member 70on the structure side is not exposed from the front cover 30, so thatthe rotation restriction member 70 can be housed within the front cover30.

Whereas, when a shape of the rotation restriction member 70 determinesthat weight of the front cover side of the rotation restriction member70 lighter than that of the structure side thereof located across thefulcrum 31, an angular moment works on the rotation restriction member70 counterclockwise around the fulcrum 31 as shown in FIG. 7.

Now, an aspect when the front cover 30 is closed regarding the structure2 is described on condition that the rotation restriction member 70having a shape determining a relation that weight of the front coverside of it is lighter than that of the structure side located across thefulcrum 31 is described with reference to FIGS. 8A, 8B, and 8C.

As shown in FIG. 8A, a protrusion section 2 c is formed in the structurefront cover holding section 2 a. Thus, when the front cover 30 becomesthe closed state from the opening state, the rotation restriction member70 rotates contacting the contact surface 30 b until the front cover 30has been closed by a given angle. Subsequently, the rotation of therotation restriction member 70 is stopped when it contacts theprotrusion section 2 c as shown in FIG. 8B. Subsequently, the frontcover 30 is closed maintaining a current posture of the rotationrestriction member 70 as shown in FIGS. 8B and 8C.

Hence, as shown there, the rotation restriction member 70 can be housedwithin the front cover 30 without an end of the structure side of therotation restriction member 70 being exposed from the front cover 30.

Now, another aspect when the front cover 30 is closed regarding thestructure 2 on condition that the rotation restriction member 70 isshaped so that weight of the front cover side is lighter than that ofthe structure side located across the fulcrum 31 is described withreference to FIGS. 9A to 9C.

As shown in FIG. 9A, the rotation restriction member 70 and the frontcover 30 are connected to each other by a tension spring 71. Thus, anangular moment is working clockwise on the rotation restriction member70 around the fulcrum 31 due to the tension spring 71 when the frontcover 30 is opened as shown in FIG. 7. When the front cover 30 is closedfrom this state, the rotation restriction member 70 keeps its posturecontacting the contact surface 2 b while receiving the angular momentfrom the tension spring 71 until the front cover 30 makes a given angle.After that, when the angular moment on the rotation restriction member70 applied from the tensile spring 71 disappears due to a relativechange in angle formed between the rotation restriction member 70 andthe front cover 30 as shown in FIG. 9B, the rotation restriction member70 leaves the contact surface 2 b. Further, when the front cover 30 iscompletely closed, the rotation restriction member 70 is brought to astate as shown FIG. 9C.

Hence, as shown in FIG. 9C, the rotation restriction member 70 can behoused within the front cover 30 without an end of the rotationrestriction member 70 on the structure side being exposing from thefront cover 30.

Further, as shown in FIG. 10, to the contact surfaces 30 b and 2 b ofthe front cover 30 and the structure 2 contacting the rotationrestriction member 70, respectively, elastic members 72 are attached,respectively. Hence, an impact created when the front cover 30 is openedand the rotation restriction member 70 contacts the contact surface 30 bof the front cover 30 and/or the contact surface 2 b of the structure 2can be absorbed and reduced by each of the elastic members 72. Here, theelastic member 72 can be only attached to one of the contact surfaces 30b and 2B.

Further, yet another example to reduce the impact caused when therotation restriction member 70 contacts the contact surface 30 b of thefront cover 30 is described with reference to FIGS. 11A and 11B.

As shown there, a plate spring 74 is fixed to the rotation restrictionmember 70 by a screw 73. When the front cover 30 is opened making agiven angle, the contact surface 30 b of the front cover 30 contacts theplate spring 74 as shown in FIG. 11A. Subsequently, as the front cover30 is further opened, the plate spring 74 is gradually bent and bearsthe weight of the front cover as shown in FIG. 11B. Hence, since a loadapplied by the front cover 30 to the rotation restriction member 70 isrelaxed by the plate spring 74, the impact caused when the rotationrestriction member 70 contacts the contact surface 30 b of the frontcover 30 can be reduced proportionally.

In this embodiment of the printer 100, when the front cover 30 and therotation restriction member 70 are assembled in the structure 2, afulcrum pin 31 a is inserted to penetrate holes formed in the structurefront cover holding section 2 a, the rotation restriction member 70, andthe front cover frame section 30 a as shown in FIG. 12A. Further, asshown in FIG. 12B, a rotation restriction member holding section 30 c isprovided in the front cover 30 to maintain the rotation restrictionmember 70 with a pair of ribs 30 d.

The rotation restriction member holding section 30 c holds the rotationrestriction member 70 with the pair of ribs 30 d to locate the holesformed in the rotation restriction member 70 and the front cover 30 onthe same linier line when the fulcrum pin 31 a is not yet insertedthereinto.

Hence, since the front cover 30 and the rotation restriction member 70is able to be assembled in the structure 2 by relatively aligning theholes of the rotation restriction member 70 and the front cover framesection 30 a, the fulcrum pin 31 a can be easily attached thereto.

FIG. 14A is an enlarged view illustrating the rotation restrictionmember 70 and its vicinity when a front cover angle adjustment screw 75is attached to the front cover frame section 30 a and the front cover 30is opened. FIG. 14B is an enlarged view illustrating the rotationrestriction member 70 and its vicinity when the front cover 30 is openedby a smaller angle than that in FIG. 14A.

In FIGS. 14A and 14B, the front cover angle adjustment screw 75 isattached to the front cover frame 30 a to adjust the opening angle ofthe front cover 30, the opening angle of which is restricted by therotation restriction member 70. Specifically, when the front cover 30 isopened, a tip of the front cover angle adjustment screw 75 contacts therotation restriction member 70, and an opening angle of the front cover30 is restricted in accordance with a contacting position.

Further, when the front cover angle adjustment screw 75 is rotatedcounterclockwise when viewed from above the apparatus, the tip of thefront cover angle adjustment screw 75 parts from the rotationrestriction member. Hence, a contact position between the tip of frontcover angle adjustment screw 75 and the rotation restriction member 70moves in a front cover opening direction, so that an opening angle ofthe front cover becomes increases as shown in FIG. 14A. Accordingly, avariation in opening angle of the front cover 30 caused by uneven partscaused by a manufacturing process can be adjusted by the front coverangle adjustment screw 75. By contrast, when the front cover angleadjustment screw 75 is rotated clockwise when viewed from above theapparatus, the tip of the front cover angle adjustment screw 75protrudes toward the rotation restriction member. Hence, the contactposition between the tip of front cover angle adjustment screw 75 andthe rotation restriction member 70 moves in a front cover closingdirection, so that an opening angle of the front cover decreases asshown in FIG. 14B.

Hence, the above-described various embodiments of the present inventionfeature per embodiment as described below.

According to one embodiment of the present invention, an apparatus canbe downsized while restricting an opening angle of the pivotable cover.

According to one embodiment, an image forming apparatus includes astructure having an image formation device to form an image, a coverpivotally attached to the structure around a rotary shaft, and anopening angle restricting device to restrict an opening angle of thecover regarding the structure. The opening angle restricting deviceincludes a pivotable cover rotation restriction member coaxiallyprovided with the rotary shaft to contact a downstream side of thepivotable cover in a cover opening direction at its first end torestrict the rotation of the pivotable cover in the opening direction.With this, an opening angle of the pivotable cover can be restrictedwhile downsizing an apparatus.

According to another embodiment of the present invention, the pivotablecover rotation restriction member further includes a second endcontacting a contact surface provided in the structure, the second endbeing arranged on an opposite side of the rotary shaft to the first end.When the pivotable cover is opened and the first end of the pivotablecover rotation restriction member contacts the downstream side of thepivotable cover in the cover opening direction, the pivotable coverrotation restriction member is pressed and rotated by the pivotablecover around the rotary shaft, while the second end of the pivotablecover rotation restriction member contacts the contact surface of thestructure and stops rotating and supports the pivotable cover byrestricting rotation and an opening angle of the pivotable cover in theopening direction regarding the structure. With this, an opening angleof the pivotable cover can be restricted downsizing an apparatus.

According to another embodiment of the present invention, the pivotablecover rotation restriction member has a prescribed shape determining arelation that a portion of the first end is heavier than a portion ofthe second end across the rotary shaft. With this, when the pivotablecover is closed, the end of the structure side of the pivotable coverrotation restricting member does not deviate from the end of thepivotable cover, and the pivotable cover rotation restriction member canbe entirely installed within the pivotable cover.

According to another embodiment of the present invention, the pivotablecover rotation restriction member has a prescribed shape determining arelation that a portion of the first end is lighter than a portion ofthe second end. The structure includes a protrusion section to contactand restrict rotation of the pivotable cover rotation restriction memberwhen the pivotable cover is closed. With this, when the pivotable coveris closed, the end of the structure side of the pivotable cover rotationrestriction member does not deviate from the end of the pivotable cover,and the pivotable rotation restriction member can be entirely installedwithin the pivotable cover.

According to another embodiment of the present invention, a spring isprovided to connect the pivotable cover rotation restriction member withthe pivotable cover to cause an angular moment on the one side of thepivotable cover rotation restriction member around the rotary shaft. Thepivotable cover rotation restriction member is shaped so that a portionof the first end is lighter than a portion of the second end across therotary shaft. With this, when the pivotable cover is closed, the end ofthe structure side of the pivotable cover rotation restriction memberdoes not deviate from the end of the pivotable cover, and the pivotablerotation restriction member can be entirely installed within thepivotable cover.

According to another embodiment of the present invention, an elasticmember is disposed at at least one of a first contact point on thedownstream side of the pivotable cover in its opening directioncontacted by the pivotable cover rotation restriction member, and asecond contact point on the contact surface of the structure contactedby the pivotable cover rotation restriction member. Hence, impact causedwhen the pivotable cover is opened can be reduced and absorbed by theelastic member.

According to another embodiment of the present invention, the pivotablecover rotation restriction member includes a plate spring contacting thedownstream side of the pivotable cover in its opening direction when thepivotable cover is opened. Hence, the impact caused when the pivotablecover is opened can be reduced and absorbed by the spring.

According to another embodiment of the present invention, an openingangle adjusting device is provided to adjust the opening angle of thepivotable cover regarding the structure restricted by the opening anglerotation restricting device. Hence, according to this, since the frontcover and the rotation restriction member are assembled in the structureby relatively aligning the holes of the rotation restriction member andthe front cover frame section, the fulcrum pin can be easily attachedthereto.

According to another embodiment of the present invention, an openingangle adjusting device is to adjust the opening angle of the pivotablecover regarding the structure restricted by the opening angle rotationrestricting device. With this, a variation in opening angle of the frontcover caused by uneven parts produced during a manufacturing process canbe adjusted.

What is claimed is:
 1. An image forming apparatus, comprising: astructure including an image formation device to form an image; a coverpivotally attached to the structure around a rotary shaft such that therotary shaft is inside ends of the pivotable cover; and an opening anglerestricting device configured to restrict an opening angle of the cover,the opening angle restricting device including a pivotable coverrotation restriction member coaxially arranged with the rotary shaftinside the cover to contact a downstream side of the pivotable cover ina cover opening direction at a first end of the pivotable cover rotationrestriction member to restrict the rotation of the pivotable cover inthe opening direction, wherein the pivotable cover rotation restrictionmember further includes a second end contacting a contact surfaceprovided in the structure, the second end being arranged on an oppositeside of the rotary shaft to the first end, and when the pivotable coveris opened and the first end of the pivotable cover rotation restrictionmember contacts the downstream side of the pivotable cover in the coveropening direction, the pivotable cover rotation restriction member ispressed and rotated by the pivotable cover around the rotary shaft,while the second end of the pivotable cover rotation restriction membercontacts the contact surface of the structure and stops rotating andsupports the pivotable cover by restricting rotation and an openingangle of the pivotable cover in the opening direction.
 2. The imageforming apparatus as claimed in claim 1, wherein, the pivotable coverrotation restriction member is not exposed from within the opening whenthe pivotable cover is closed.
 3. The image forming apparatus as claimedin claim 1, further comprising an elastic member disposed at at leastone of a first contact point on the downstream side of the pivotablecover in its opening direction contacted by the pivotable cover rotationrestriction member, and a second contact point on the contact surface ofthe structure contacted by the pivotable cover rotation restrictionmember.
 4. The image forming apparatus as claimed in claim 1, whereinthe pivotable cover rotation restriction member includes a plate springcontacting the downstream side of the pivotable cover in its openingdirection when the pivotable cover is opened.
 5. The image formingapparatus as claimed in claim 1, wherein the pivotable cover, thestructure, and the pivotable cover rotation restriction member,respectively, have multiple holes therein to collectively acceptinsertion of the rotary shaft when assembled, wherein the pivotablecover includes a holder section to hold the pivotable cover rotationrestriction member to align the respective holes of the pivotable cover,the structure, and the pivotable cover rotation restriction membersubstantially along the same linear line during assembly.
 6. The imageforming apparatus as claimed in claim 1, further comprising an openingangle adjusting device to adjust the opening angle of the pivotablecover when its rotation is restricted by the opening angle rotationrestricting device.
 7. The image forming apparatus as claimed in claim1, wherein a portion of the first end of the pivotable cover rotationrestriction member is heavier than a portion of the second end of thepivotable cover rotation restriction member across the rotary shaft. 8.The image forming apparatus as claimed in claim 1, wherein a portion ofthe first end of the pivotable cover rotation restriction member islighter than a portion of the second end of the pivotable cover rotationrestriction member, wherein the structure further includes a protrusionsection to contact and restrict rotation of the pivotable cover rotationrestriction member when the pivotable cover is closed.
 9. The imageforming apparatus as claimed in claim 1, further comprising: a spring toconnect the pivotable cover rotation restriction member with thepivotable cover to create an angular moment on the first side of thepivotable cover rotation restriction member around the rotary shaft,wherein a portion of the first end of the pivotable cover rotationrestriction member is lighter than a portion of the second end of thepivotable cover rotation restriction member across the rotary shaft. 10.An openable unit comprising: a structure including a prescribed device;a cover pivotally attached to the structure around a rotary shaft suchthat the rotary shaft is inside ends of the pivotable cover; and anopening angle restricting device to restrict an opening angle of thecover including a pivotable cover rotation restriction member coaxiallyarranged with the rotary shaft to contact a downstream side of thepivotable cover in a cover opening direction at its first end torestrict the rotation of the pivotable cover in the opening direction,wherein the pivotable cover rotation restriction member further includesa second end contacting a contact surface provided in the structure, thesecond end being arranged on an opposite side of the rotary shaft to thefirst end, and when the pivotable cover is opened and the first end ofthe pivotable cover rotation restriction member contacts the downstreamside of the pivotable cover in the cover opening direction, thepivotable cover rotation restriction member is pressed and rotated bythe pivotable cover around the rotary shaft, while the second end of thepivotable cover rotation restriction member contacts the contact surfaceof the structure and stops rotating and supports the pivotable cover byrestricting rotation and an opening angle of the pivotable cover in theopening direction.
 11. The openable unit as claimed in claim 10,wherein, the pivotable cover rotation restriction means is not exposedfrom within the opening when the pivotable cover means is closed. 12.The openable unit as claimed in claim 10, further comprising an elasticmember disposed at at least one of a first contact point on thedownstream side of the pivotable cover in its opening directioncontacted by the pivotable cover rotation restriction member, and asecond contact point on the contact surface of the structure contactedby the pivotable cover rotation restriction member.
 13. The openableunit as claimed in claim 10, wherein the pivotable cover rotationrestriction member includes a plate spring contacting the downstreamside of the pivotable cover in its opening direction when the pivotablecover is opened.
 14. The openable unit as claimed in claim 10, whereinthe pivotable cover, the structure, and the pivotable cover rotationrestriction member, respectively, have multiple holes therein tocollectively accept insertion of the rotary shaft when assembled,wherein the pivotable cover includes a holder section to hold thepivotable cover rotation restriction member to align the respectiveholes of the pivotable cover, the structure, and the pivotable coverrotation restriction member substantially along the same linear lineduring assembly.
 15. The openable unit as claimed in claim 10, furthercomprising an opening angle adjusting device to adjust the opening angleof the pivotable cover when its rotation is restricted by the openingangle rotation restricting device.
 16. The openable unit as claimed inclaim 10, wherein a portion of the first end of the pivotable coverrotation restriction member is heavier than a portion of the second endof the pivotable cover rotation restriction member across the rotaryshaft.
 17. The openable unit as claimed in claim 10, wherein a portionof the first end of the pivotable cover rotation restriction member islighter than a portion of the second end of the pivotable cover rotationrestriction member, wherein the structure further includes a protrusionsection to contact and restrict rotation of the pivotable cover rotationrestriction member when the pivotable cover is closed.
 18. The openableunit as claimed in claim 10, further comprising a spring to connect thepivotable cover rotation restriction member with the pivotable cover tocreate an angular moment on the first side of the pivotable coverrotation restriction member around the rotary shaft, wherein a portionof the first end of the pivotable cover rotation restriction member islighter than a portion of the second end of the pivotable cover rotationrestriction member across the rotary shaft.
 19. An image formingapparatus, comprising: means for forming an image; structure means foraccommodating the image forming means; means for covering a side of thestructure means, the covering means pivotally attached to the structuremeans around a rotary shaft such that the rotary shaft is inside ends ofthe pivotable cover means; and means for restricting an opening angle ofthe cover means including a pivotable cover rotation restriction meanscoaxially arranged with the rotary shaft to contact a downstream side ofthe pivotable cover means in a cover opening direction at its first endto restrict the rotation of the pivotable cover means in the openingdirection, wherein the pivotable cover rotation restriction meansfurther include a second end contacting a contact surface provided inthe structure means, the second end being arranged on an opposite sideof the rotary shaft to the first end, and when the pivotable cover meansare opened and the first end of the pivotable cover rotation restrictionmeans contact the downstream side of the pivotable cover means in thecover opening direction, the pivotable cover rotation restriction meansare pressed and rotated by the pivotable cover means around the rotaryshaft, while the second end of the pivotable cover rotation restrictionmeans contacts the contact surface of the structure means and stopsrotating and supports the pivotable cover means by restricting rotationand an opening angle of the pivotable cover means in the openingdirection.